Axis Communications AXIS 2420 user manual Picture frequency for Networking Applications, Max fps

32 Choosing Your Application AXIS 2420 User’s Manual

Picture frequency for Networking Applications

When used in a TCP/IP networking environment, the AXIS 2420 delivers up to 30/25 (NTSC/PAL) images/second. The perceived frame rate in your browser is typically limited by:

•the number of clients accessing the images

•your computer and browser

•the chosen image resolution and compression

•the lighting conditions at the point of installation

•available network bandwidth

•the complexity of detail and color variation within the image

Note: The AXIS 2420 is available in NTSC and PAL variants to accommodate the different power supply frequencies in the USA and Europe.

Image Compression Ratios

Although the file size of a JPEG-compressed image depends upon the actual content of the image, images containing great detail generally generate larger files. Image quality is largely controlled through the level of compression; where high compression yields small files, and low compression maintains higher image quality at the expense of larger files. The table below is derived from real-life tests, and defines the average file sizes for each supported image resolution:

	NTSC			PAL
Resolution	File size (kb)	Max fps*	Resolution	File size (kb)	Max fps*
4CIF (704 x 480)	7 - 150	10	4CIF (704 x 576)	8.5 - 180	8
CIF (352 x 240)	1.4 - 40	30	CIF (352 x 288)	1.7 - 50	25

* Maximum performance for a single viewing client.

Note: Using a modern computer will avoid introducing any unnecessary constraints on the image fre- quency.